Warburton says of this backbore "Its reverse-taper 'hourglass' design produces an intensely focussed sound. It prints exceptionally well on the mic in live performances and in the studio. The bore is 27 at the interface to match a standard top, but shrinks to #29 at the 'waist.' High PSI is required for this backbore."
Although it is certainly tight to play, using a Bach 190 trumpet and Warburton 8S top I had very little difficulty quickly getting a consistent sound over three octaves from below the staff. Articulations and slotting are very accurate and good, even below the staff. It is really easy to get a big volume of sound and full tone above the staff with very little effort (Warburton's comment that "High PSI is required" seems a bit misleading in this respect). More surprising perhaps other band memebrs commented on the 'beautiful' sound - the sound is very concentrated and if you back off and have good air support it can produce a really burnished tone. If you want that kind of intense focus this is a better bet in my view than other Warburton backbores including the NY, H and Q/Qm. I do a lot of extended playing out of doors or in large public spaces and the J29 is a great tool for that job - you get a huge amount of support from this backbore to carry you through hours of playing. For that reason I'm giving it a 5 star rating, but I'm aware that for most people the J29 is very unsuited to all round use and may be completely unacceptable if you like an open mouthpiece.
